Register link on non-WordPress page

Okay. I know I’m probably going about this all wrong, anyway, but here goes. I’m using WordPress primarily to develop Pages, not Posts, to allow visitor comments. I would like to do 2 things:

1. I have an html entry page, not in my WP folder, on which I would like to link to my WP registration and login pages:
public_html -> entry page with register and login links
public_html -> wordpress -> ?
What sort of code should I use?

2. There is a ‘back to blog’ link on the registration page that would like to direct to back to the entry page. Where should I go to change this code, (wp-register.php, I presume) and what am I looking for?

Thanks.